1. Field of the Invention
The present invention relates to ice having sterilizing power capable of sterilizing harmful germs, etc., and preventing the increase of them to increase a treatment effect in a medical field and preserve foods and drinks and keep their quality fresh in a food industry by using the ice and a method of manufacturing the ice.
2. Description of the Related Art
As proposed by the inventors of the present invention in Japanese Unexamined Patent Publication No. 9-149, there has been used, as a method of manufacturing ice having sterilizing power which will be used in a medical treatment and food preservation, a method of manufacturing ice by electrolyzing seawater or water containing sodium chloride therein to produce hypochlorous acid as hypohalogenous acid and freezing the water.
However, since seawater (sodium chloride concentration: 3.5%) or water in which sodium chloride is dissolved in an amount of about 0.3-3% is electrolyzed in the above conventional method, sodium chloride of a high concentration remains in the water in which hypochlorous acid is produced and when ice is made by freezing the water, the freezing point of the water is dropped by the remaining sodium chloride and the like. Accordingly, there arises a problem that not only a lower temperature is required to make the ice from the water but also the ice obtained by the above method is liable to melt even if it is used at a low temperature and cannot be used as the ice for a long time because the ice is soft and its freezing point is dropped.
To suppress the drop of the freezing point, the inventors of the present invention tried to produce hypochlorous acid by electrolyzing fresh water such as tap water and the like containing sodium chloride in a low concentration by using a platinum-clad-titanium electrode as an anode and make ice by freezing the water as proposed in Japanese Examined Patent Publication No. 4-28438.
In the method of using the platinum-clad-titanium electrode, however, there is a problem that an efficiency for producing hypohalogenous acid by the electrolysis is low and when the fresh water having a low electric conductivity is used, free residual halogen having a concentration sufficient to obtain sterilizing power cannot be obtained because platinum is exfoliated and the titanium electrode is exposed due to a great increase in a voltage imposed between electrodes.
An object of the present invention made in view of the above problems is to provide ice which has a free residual halogen concentration for obtaining sufficient sterilizing power and sodium chloride remaining therein in a low concentration and can be used for a long time as the ice and a method of manufacturing the ice.